The present invention relates to multi-layer materials suitable for forming into flexible containers. Specifically, the present invention relates to multi-layer materials which resist to the aggressive action of products comprising hypochlorite bleach.
A wide variety of packaging materials are known. Many of said packaging materials are in the form of materials made of different layers. Said various layers allow to obtain a composite material with a desired combination of properties otherwise not available from a single layer of a single material.
A commercially available and very cost efficient multi-layer material comprises polyethylene terephthalate (=PET) laminated with an adhesive to a polyethylene layer. Preferably, said polyethylene layer is made of low density polyethylene (=LDPE). Usually the PET is the outer layer and the LDPE is the inner layer when this multi-layer material is formed into a container, preferably into a flexible sachet or pouch. In a very common execution, sachets or pouches have flat, substantially parallel, opposed rectangular walls completely joined together by heat sealing around their peripheral edges. Specifically, the inner layers of the opposed walls made of LDPE are intimately sealed together. The resulting sachet or pouch is leak tight, and sufficiently resistant to punctures, therefore completely suitable for containing liquid products.
We found that such a container degrades when it contains a liquid product comprising a hypochlorite bleach. Indeed, the migration of said hypochlorite bleach, or components of said bleach, through said LDPE layer towards the outside of said container is not prevented, specifically towards the adhesive layer of said container. Consequently, said adhesive between the LDPE layer and the outer PET layer is exposed to said bleach or said bleach component(s). As a result, said adhesive may be decomposed, whereby losing its bonding properties. Therefore, the PET layer may de-laminate partially or completely from the LLDPE layer. Eventually, the containment properties of said container are degraded, if not completely lost.
It is therefore an object of the present invention to provide a multi-layer material, whose containment properties when formed into a container do not degrade, when said container contains a liquid product comprising a hypochlorite bleach.
The present invention is a multi-layer material for containing liquid products comprising hypochlorite bleach. This multi-layer material comprises an inner layer, a layer of adhesive and an outer layer. Said inner layer is made of a heat sealable polyolefin, and said outer layer is made of a printable plastic material. Said multi-layer material further comprises a means which prevents that said multi-layer material degrades with the aggressive action of said hypochlorite bleach or components of said bleach. Preferably, said multi-layer material according to the present invention comprises a barrier layer and/or a bleach resistant adhesive layer.